1. Field of the Invention
The present invention relates to a metal fixture embedded in a dust cover for fixing the dust cover at an installation position.
2. Description of the Conventional Art
As illustrated in FIG. 6, a dust cover 52 is conventionally utilized for protecting a rocking operation part of a ball joint 51, and a metal fixture 55 for fixing the dust cover 52 to a joint socket 54, which is a counterpart for mounting, is embedded in a fixing section 53 at one end of the dust cover 52.
As illustrated in FIG. 7 (A) enlargedly, the metal fixture 55 is formed by pressing of a metal plate. Conical surface shaped inner diameter teeth 58, which are for setting a fitting tolerance with respect to the joint socket 54, are integrally formed at one end in the axial direction (at a lower end in the figure) of an outer diameter tube section 56 via a bend 57 in between (refer to Japanese Patent Application Laid-Open No. 8-303447 (FIG. 1)).
Further, as illustrated in FIG. 7 (B), the metal fixture 55 is inserted into a mold 59 at a time of forming of the dust cover 52 made of an elastic body by the mold 59, and embedded in the dust cover 52 at the same time of the forming of the dust cover 52 (an insert molding).
Furthermore, as illustrated in FIG. 7 (A), in a state of being embedded in the dust cover 52, the metal fixture 55 is embedded at a position retreated in the axial direction by a predetermined distance d from an end face 52a of the dust cover 52 in order to decrease an exposure area to outside air as much as possible. Thus, as illustrated in FIG. 7 (B), in order to fix the metal fixture 55 at a predetermined vertical position when the metal fixture is inserted into the mold 59, a plurality of pins 60 for specifying the vertical position of the metal fixture are erected on an inner face of the mold 59. Therefore, since the dust cover 52 is molded under the state that the metal fixture 55 is placed on the pins 60, a plurality of recessions 61, which are left after pulling-out of the pins 60, are formed on the end face 52a of the dust cover 52 when the molded dust cover 52 is taken out from the mold 59 after molding.
However, the aforementioned conventional technique has the following problems.
When the mold 59 is used for a long period of time, top ends of the pins 60 contact to the metal fixture 55 repeatedly so as to be worn gradually. Thus, completed products have variation in the metal fixture embedding position. Therefore, it takes much work, time, and cost to make maintenance of the mold 59 to prevent the variation. Since it is necessary to erect the pins 60 in the mold 59, a production cost of the mold 59 increases.
Further, in case of the structure that the pins 60 are erected in the mold 59 and the metal fixture 55 is placed on the pins 60, an axial-directional dimension L1 of the dust cover fixing section 53 increases by the heights of the pins 60. Therefore, when the attaching space of the fixing section 53 is restricted, it is difficult to adjust the axial-directional dimension L1.
Furthermore, Japanese Utility Model Publication No. 54-118553 (FIG. 2) discusses another conventional technique in which a bottom face of a metal fixture of a dust cover is formed in a shape waving in a circumference direction. However, when the metal fixture having such the shape is embedded in the dust cover so as to set the bottom face at the same position in the axial direction as one end face in the axial direction of the dust cover, many radial straight lines due to the waving shape are formed as metal exposure sections at the one end face in the axial direction of the dust cover. Therefore, according to this conventional technique, a metal exposure area with respect to a rubber surface should be increased, so that there is a problem that the metal fixture is corroded easily.